MODIS Land Data Formats and Access MODIS Science
- Slides: 12
MODIS Land Data Formats and Access MODIS Science Team Meeting (Land Discipline Breakout Session) July 13, 2004 Robert Wolfe Raytheon ITSS @ NASA GSFC Code 922 July 12, 2004 - Wolfe - MODLAND Mtng.
Land Algorithm Dependency Input Data Previous Period’s Calibrated Radiance Geolocation Fields Cloud Mask Aerosol Precipitable Water DAO Data BRDF/Albedo Land Surface Temp. /Emissivity Land Cover L 2/L 2 G Products Snow/Sea-Ice Cover Land Surface Temp. /Emissivity Surface Reflectance Fire Grid Pointer Data Grid Angular Data Previous L 3/L 4 Products Snow/Sea-ice Cover Surface Reflectance Land Surface Temp. /Emissivity Fire and Burned Areas Vegetation Indexes BRDF/Albedo LAI/FPAR GPP/NPP Land Cover and Vegetation Dynamics Vegetation Cover Change and Continuous Fields Evapotranspiration July 12, 2004 - Wolfe - MODLAND Mtng. 3
Product Format • Hierarchical Data Format (HDF) – Self describing file format • Science Data Sets (SDSs) – 2 D, 3 D or 4 D arrays – Bit Fields – unsigned integers broken into groups of bits – Discrete values – e. g. , Snow, Cloud, etc. – Scaled Integers – valid range, scale and offset included • Attributes – text or other data that annotates the file (global) or arrays (SDSs) • Metadata – ECS metadata for products (stored as attributes) – includes QA information, date/time products acquired/produced, etc. • . met file contains the ECS core metadata – some additional fields – some fields (QA, etc. ) may be updated when product distributed • HDF-EOS Metadata (SWATH or GRID) – geometric information that relates data to specific earth locations July 12, 2004 - Wolfe - MODLAND Mtng. 4
Level 2 Products • Retrieved geophysical parameters at the same location and in the same format as the MODIS Level 1 instrument data – 288 granules/day; 5 min. ; approx. 2340 x 2030 km – 250 m, 500 m and 1 km nadir resolutions July 12, 2004 - Wolfe - MODLAND Mtng. 5
Level 2 G, 3 and 4 Products (fine resolution) Sinusoidal • Level 2 G/3: earth-gridded geophysical parameters • Level 4: earth-gridded model outputs • Daily, 8 -day, 16 -day, 32 -day, monthly and yearly products • Fine resolution grid(s) – 10º x 10º Tiles: – Sinusoidal (equatorial); 7. 5, 15 and 30 arcsec. resolution (roughly 250 m, 500 m and 1 km) – LAEA (sea-ice products, polar projection) Lambert Azimuthal Equal Area (LAEA) July 12, 2004 - Wolfe - MODLAND Mtng. 6
Climate modeling grid products • Resolution: 0. 05º (now) and 0. 25º (previous) degrees • Almost all products are lat/long – sea-ice is current exception – in polar grid (snow in C 5) July 12, 2004 - Wolfe - MODLAND Mtng. (from BU – NBAR CMG – days 193 -208, 2001) 7
MODIS products per day @ 1 X* Produced by Product Generation Executives Volume GB/day Files/day Level 0 EDOS N/A 67 12 Level 1+ GES DAAC MODAPS 6 DAAC 2 MODAPS 235 4, 500 2, 400 Atmos 2, 950 Oceans Type Oceans SST, Atmospheres MODAPS 16 18 Atmos 80 SST Land MODAPS 27 330 9, 500 Snow/Sea Ice MODAPS 9 12 2, 300 60 742 24, 600 Totals * Sustained processing rate is currently 6 X (4 X for reprocessing + 1 X forward Terra + 1 X forward Aqua) July 12, 2004 - Wolfe - MODLAND Mtng. 8
Getting MODIS Data • Order from DAAC through EOS Data Gateway – response is a few hours – services (e. g. subsetting) available for some products • Get data from DAAC data pools – most recently produced data are online and available via FTP • Get data from other sources (Science team sites, MODIS Rapid Response, direct broadcast, etc. ) July 12, 2004 - Wolfe - MODLAND Mtng. DAAC Unique Ordering Interfaces 9
MODIS Data Distribution • MODIS DAACs distribute more than 1. 3 TB/day of MODIS standard products – about 130, 000 product files/day – Land products distributed from EDC and NSIDC DAACs are about 1/3 of the total • Science team and other non-DAAC distribution (rapid response) add an additional 0. 1 TB/day July 12, 2004 - Wolfe - MODLAND Mtng. 10
DAAC distribution services • Subsetting via. EDG (through HEW Subsetting Appliance) – Only implemented at NSIDC – all products (except CMGs) • Service for products in Data Pools using HEG – Spatial and parameter subsetting • NSIDC: all product except CMGs • EDC LP: phased release – some product already released – Compression – Gzip, Zip, Unix compression (. gz, . zip, . z) – Format conversion • NSIDC: L 2 products currently (L 2 swath); other products soon • EDC all products (as released) – Newly installed ECS version 6 A. 07 system has capability to stage data through data pools – so users “should” be able to apply Compression and Format Conversion by first ordering the data using EDG and then performing the services before downloading data • USGS seamless distribution system (spatial and parameter subsetting, compression and format conversion) – currently only 500 m 16 -day VI/EVI (MOD 13 A 2 for 2000 to 2003) • Data mining script for data pools (MODextract) – works for L 3 tiles for user specified date range – finds and downloads data automatically July 12, 2004 - Wolfe - MODLAND Mtng. 11
DAAC developed/supported user tools • MODIS Reprojection Tools (EDC LP DAAC) – both grid and swath (new) – reprojection (resampling) – also: spatial subsetting, parameter subsetting, mosaics and format conversion • LDOPE tools (EDC LP DAAC) – (see Roy’s slides) July 12, 2004 - Wolfe - MODLAND Mtng. 12
Other tools http: //hdfeos. gsfc. nasa. gov/hdfeos HDF-EOS Tools User Forum can be useful for new EOS data users (same site) July 12, 2004 - Wolfe - MODLAND Mtng. 13